|Posted: Wed May 22, 2019 8:29 am Post subject:
|DConvert, Adding my personal garage level experience with over the counter solvents... Hopefully it will compliment your lab experience.
I can confirm that hardware store naptha does soften vinyl work mats and may remove lens element paint. It also evaporates somewhat slower and cuts through oil (tar and grease) nicely.
When cleaning the entire surface of an assembled lens I try to avoid any solvents that evaporate super fast like denatured alcohol or iso-propyl 90%. I only use those solvents when the element is open and separate from the lens housing.
What I have noticed is that the rapid evaporation is causing cooling of the element, which may draw condensation into the backside group or housing.
The most critical personally; Decreased work time because of rapid evaporation may find yourself with no solvent to float the oils while wiping.
Adding a slower evap solvent like Zeiss lens cleaner after applying a rapid evaporating solvent can help with post cleanup of oils without the possibility of ending up with a dry scratchy texwipe, pecpad, cotton swab or kimwipe.
Also note that there is a good chance that many solvents will require the side of an element to be re-painted black.
Any hydrocarbon solvent will be likely to do all the things you mentioned. Depending on your desired rate of evaporation gasoline, lighter fluid, white spirit, kerosene, or diesel could all be used (listed in decreasing volatility) the last few will leave residues that don't simply evaporate away.
I'm not sure quite what American 'hardware store naptha' is, but I suspect it's a paint thinner/brush cleaner like our white spirit - a turpentine substitute (sometimes sold under that name at higher prices).
Within each of the volatility ranges there will be a wide range of compositions (I've seen hundreds of different gasolines - some very different from each other) which will cause differences in solvency. A highly paraffinic solvent will have less solvency and so be less likely to remove paint or attack plastics, but will still swell rubber & lift most oils etc. Highly aromatic formulations have better solvency but are more harmful both to you & to plastics etc.
The elements I'm currently working on are proving difficult to get totally clear even using aggressive solvents like acetone, but they are gradually improving - you could barely see through them when I started, now after two tries they've almost reached the point where I wouldn't have felt the need to strip them from the lens i.e. almost good enough that I could make do, certainly not good enough to consider done.